Engine systems for vehicles and the like may comprise an aftertreatment module for removing unwanted gaseous emissions or pollutants from the exhaust gases of an internal combustion engine. In particular, a selective catalytic reduction (SCR) system may be provided in the exhaust gas stream for removing nitrogen oxides (NOx). Typically, an SCR system comprises a reductant injector reaching into a mixing pipe located upstream of a catalyst. The reductant injector may inject a liquid reductant into the exhaust gases before they contact the catalyst. Suitable liquid reductants may include anhydrous ammonia, aqueous ammonia and urea. The high temperature of the exhaust gases may evaporate the liquid reductant, and upon contact with the catalyst, the gaseous reductant may react with the NOx in the exhaust gas to form nitrogen and water.
However, if the exhaust gas temperature is too low, such as during low engine load conditions and in low duty cycles, the reductant may be deposited as solid compounds on components of the SCR system. In particular, the reductant may be deposited on or around an outlet nozzle of the reductant injector when eddy currents in the exhaust gas flow redirect injected reductant back onto the outlet nozzle. In addition, the reductant may crystallize and form deposits inside the reductant injector.
For example, WO 2015/153350 A1 discloses an anti-clogging device for a diesel exhaust fluid (DEF) supply, wherein a reservoir for air trapped in a feed line for supplying DEF to a dosing module is placed vertically above the dosing module.
The present disclosure is directed, at least in part, to improving or overcoming one or more aspects of prior systems.